Player piano key actuating solenoid valve assembly



Feb. 4, 1969 R. CANNON ETAL 3,426,304

PLAYER PIANO KEY ACTUATING SOLENOID VALVE ASSEMBLY Filed Oct. 6. 1966 A M/M20 A. 'Aw/vav 0/02155 A2 M0955 Z 2%, w /ffa $7M flrmpA/t-ys United States Patent 3,426,304 PLAYER PIANO KEY ACTUATING SOLENOID VALVE ASSEMBLY Richard Cannon and Charles M. Morse, Yankton, S. Dak., assignors to Dale Electronics, Inc., Columbus, Nebn, a corporation of Nebraska Continuationin-part of application Ser. No. 503,043, Oct. 23, 1965. This application Oct. 6, 1966, Ser. No. 584,885 US. Cl. 335-255 16 Claims Int. Cl. H01f 3/00, 7/ 08; G10f 3/00 ABSTRACT OF THE DISCLOSURE A device for converting conventional pianos to player pianos including a holding fixture for solenoid key actuating units wherein the solenoid units are arranged in side by side horizontal relationship or in vertical staggered relationship for engaging the piano keys. The fixture for one row of solenoid units includes a pair of oppositely facing channel members having leg portions engaging opposite ends of the solenoid units whereby the holding fixture channels serve as a common magnetic path for the individual solenoid coils and as a heat sink to dissipate heat directly from the coils.

This application is a continuation-in-part of our copending application entitled Player Attachment for Pianos and the Like, Ser. No. 503,043 filed Oct. 23, 1965.

The key actuating assemblies for pianos may be of two types; the direct-blow and the drop action. The direct blow action will normally have the key actuating assembly mounted under the keyboard. It the key actuating assembly is mounted over the keys it will normally be mounted in such a way that the push rods push down against the keys.

Thus it is one of the principal objects of this invention to provide a holding fixture for solenoid key actuating units wherein the holding fixture serves as a common magnetic path for the individual solenoid coils and as a heat sink to dissipate heat directly from coils.

A further related object of this invention is to provide a holding fixture for key actuating solenoid units wherein the solenoid units may be readily horizontally moved relative to the holding fixture.

A still further object of this invention is to provide a piano key actuating solenoid valve having a cushioning means for absorbing the sound caused by the metal plunger moving against the metal tubular member.

Yet another object of this invention is to provide a player piano key actuating assembly which may be quickly and easily assembled and adjusted on the piano as desired.

A still further object of this invention is to provide a player piano actuating assembly including first and second solenoid mounting channel assemblies in vertically aligned relationship whereby the push rods of the solenoids in the lower row of solenoids extends between the channel members of the upper row of solenoids such that the push rods of each row of solenoids are in common plane and thus can. engage the lever arms of the piano keys at an equal distance from their pivotal axes and consequently provide a uniform sound volume from the action of each piano key.

A related object of this invention is to provide a player piano key actuating assembly including a pair of vertically spaced apart rows of solenoids having push rods in a common vertical plane and having collar elements on each of the push rods to limit the retraction of the push rods into the solenoid body and a sound absorbent means being provided on the push rods between the collars and the solenoid body to minimize the operating noise of the solenoids.

Yet another related object of this invention is to provide a player piano key actuating solenoid valve assembly including a pair of vertically aligned rows of solenoids supported by two pairs of spaced apart channel members interconnected by a mounting plate and one channel member of each row of solenoids having a terminal plate on the opposite side from the mounting plate.

A further object of this invention is to provide a player piano key actuating solenoid valve assembly which is simple in design, economical to manufacture and refined in appearance.

These and other objects will be apparent to those skilled in the art.

This invention consists in the construction, arrangements, and combination of the various parts of the device, whereby the objects contemplated are attained as hereinafter more fully set forth, specifically pointed out in the claims, and illustrated in the accompanying drawings in which:

FIG. 1 is a fragmentary perspective view of the player piano key actuating solenoid valve assembly oriented for use on the direct blow action-type piano;

FIG. 2 is an exploded perspective view of the key actuating solenoid valve assembly; and

FIG. 3 is a fragmentary perspective view of an alternate embodiment of this invention wherein the piano key actuating solenoids are vertically arranged such that the push rods extend in a common plane.

The player piano key actuating assembly of this invention is referred to in FIG. 1 generally by the reference numeral 10. Although the key actuating assembly 10 may be used on either the direct or drop action-type piano, it is illustrated in FIG. 1 for use on the direct-type wherein the push rods of the solenoid valves push against the underside of the keys. The conventional piano structure including the keys is not illustrated in the drawings but may be of the type fully disclosed in our co-pending application, Ser. No. 503,043.

A solenoid valve assembly is shown in FIG. 2 and includes a plunger 12 having an annular groove 14 at its outer end. A push rod 16 is press-fitted into the inner end of the plunger 12. The inner end of the push rod 16 is knurled at 18 to provide for the press-fit in the plunger 12. The outer end of the push rod 16 is provided with a doll or shoulder portion 20 having a disc-shaped felt element 22 mounted thereon. The plunger 12 and the push rod 16 are formed of a metal material such as steel and are fitted into a tubular member 24 having a'flared end 26. An insulative washer 28 is pressed over the tube along its full length until it is in engagement with the flared end portion 26. An insulative sleeve 30 of preferably Mylar material and being very thin is then slipped over the brass tube 24 and set directly against the previously fitted insulated washer 28. Next, another insulative washer 32 is pressed over the brass tube and snapped into an annular groove 34 formed in the other end of the tubular member 24 thereby locking the Mylar sleeve against relative longitudinal movement. This assembly thus forms the bobbin on which a coil 35 is wound. It is seen that the coil 35 is completely insulated from the brass tube 24 by the Mylar sleeve 30 and the insulative washers 28 and 32.

An adapter element 36 having a circular cross-section portion 38 is press-fitted into the flared end 26 of the tube 24. The opposite end of the adapter 36 is threaded at 40 to receive a nut 42. A substantially larger in diameter portion is provided intermediate the ends 38 and 40 and is provided with a pair of parallel vertical shoulder 43 which intersect with horizontal shoulders 44.

The solenoid unit just described is then placed between a pair of oppositely facing channel members having top adjacent side legs 52 and bottom adjacent side legs 54. Each of the channel members 50 is provided with a vertically disposed bottom wall 53. The vertically disposed parallel shoulders 43 on the adapter 36 matingly engage the inner edges of the side legs 52 and thus prevent any rotational movement of the solenoid assembly. The nut 42 in engagement with the side legs 52 through a washer 56 holds the solenoid unit against any transverse movement relative to the pair of channel members 50. Additionally, the insulative washer 32 is adapted to bear against the bottom pair of adjacent channel side legs 54 to limit transverse movement of the solenoid relative to the channel members 50. The flared end portion 26 of the brass tube 24 it is seen bears against the bottom surface of the horizontally disposed shoulders 44.

It is apparent that by selective adjustment of the nut 42 the solenoid assembly may be selectively positioned between the pair of channel members 50 and that any number of solenoid units that is desired may be placed side by side in the holding fixture formed by the pair of channel members 50.

A second pair of channel members 50A having similarly constructed solenoid valve assemblies disposed therein are secured to the first pair of channel members 50 through an insulator terminal board 70 by bolt fastener elements 72. Thus the four channels function together to form a holding fixture for the solenoid units and provide a common magnetic path for the individual solenoids as well as to provide a heat sink to dissipate heat directly from the coils through the entire length of the four channels.

The inner end of the adapter 36 is provided with a cavity 80 in which a rubber cushioning element 82 is mounted and embraces the push rod 16 for cushioning and quieting the operation of the solenoid valve assembly.

Below the two sets of channel members 50 and 50A a channel member 90 which is disposed in a downwardly facing manner is positioned. A sheet of felt cushioning material 92 is provided below each pair of channel members 50 and 50A respectively on opposite sides of the terminal board 70. A series of brackets 94 are fastened to the bottom sidewalls 53 of the outer channel members 50 and to the downwardly extending sidewall leg portions 96 of the stop plate channel member 90. An elongated slot 98 is provided in the bracket elements 94 so that the stop plate channel member 90 may be selectively positioned at any desired distance below the bottom ends of the plungers 12.

In the event that the channel fixtures 50 and 50A with the associated solenoid valve units is used on a drop action-type piano wherein the push rods operate downwardly on the piano keys, then it would be necessary to provide a spring means as illustrated in our co-pending application, Ser. No. 503,043 to return the plungers 12 to their inoperative positions. The spring in this event would be engaged in the annular groove 14 in the plunger 12 and the stop channel member 90 would not be employed. It is obvious that the entire assembly as illustrated in FIG. 1 would be inverted for use on the drop action-type piano.

Thus it is seen that the brass tubes 24 in comparison to common molded tubes serve to provide a substantial bearing surface for the plungers 12 as well as provide a solid holding fixture for the coils 35 to be wound on and additionally provide a direct metal to metal conductive means through adapter 36 between the tubular members 24 and the fixture channels 50 and 50A to dis- .sipate the heat generated by the coils 35.

On the direct blow-type pianos it is seen that the cushioning felt sheet material 92 serves to dampen or deaden the return stroke of each of the plungers 14. Also the stop channel 90 may be selectively vertically adjusted to allow for fine adjustments of the plunger stroke length which is sometimes necessary for some piano actions having a slight warp or otherwise non-uniform in fit.

Referring now to FIG. 3 two rows of solenoids 100 and 102 are shown in vertically spaced apart relationship. Each row includes a pair of channel members 50B facing each other for supporting engagement with the solenoid units illustrated in FIG. 2. A solenoid unit 104 is provided in the channel members 50B of the row 100 and has a push rod 106 extending upwardly therefrom with a doll 108 on the outer end thereof. A collar 110 is slidably adjustable on the push rod 106 and may be locked in any desired position by a set screw 112. An insulating cushion element 114 is provided on the top of the solenoid body or adapter element 36 to cushion the action of the collar member 110 upon retraction of the push rod into the solenoid. A solenoid 116 is mounted in the pair of channel members 102 in the bottom row and is provided with a push rod 118 which is sufficiently long in length to extend upwardly between the channel members 50B in the upper row 100 and terminate adjacent the upper end of the push rod 106 of the solenoid unit 104. A doll 108 is also provided on the upper free end of the push rod 118. A disc-shaped felt element 22 is provided on the outer end of each of the dolls 108 to cushion the engagement of the dolls with the lever arms of the piano keys.

The solenoid unit 116 in the bottom row 102 is also provided with a cushioning disc element 114 and an adjustable collar 112 to limit the retraction of the push rod 118.

A mounting plate 120 is provided which extends between the two rows of solenoids 100 and 102 and is connected to the base portions of adjacent channel members in each row. The plate 120 thus serves to maintain the rows of solenoids in the desired spaced apart vertical relationship.

A terminal plate member of insulative material 122 is provided along the length of the base portion of each of the other channel members 50B in each of the rows 100 and 102.

It is to be understood that the solenoids 104 and 116 are mounted in their respective channel members 50B in the same manner as is illustrated in FIG. 1. The adjustable collars 112 make it possible to eliminate the stop plate channel member 90 and the associated sheet of felt cushioning material 92. Each of the push rods are provided with their own separate cushioning felt sheet elements 114.

It is thus seen that through the use of the solenoid actuating assembly of FIG. 3 a uniform piano sound volume Will be provided for each of the piano keys since the push rods will engage all piano keys at the same distance from their pivotal axes because the two rows of solenoids are vertically arranged.

Some changes may be made in the construction and arrangement of our player piano key actuating solenoid valve assembly without departing from the real spirit and purpose of our invention, and it is our intention to cover by our claims, any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

We claim:

1. A player piano key actuating assembly, comprising, a pair of spaced apart oppositely facing metalic channel members, and a solenoid valve assembly held between said pair of channel members, and including a metalic tubular member, a plunger movably disposed in said tubular member, means securing one end of said tubular member to adjacent sides of said channel members to limit transverse movement between said channel members, an adaptor member rigidly secured in the other end of said tubular member and extending outwardly between the other pair of adjacent sides of said channel members, and means engaging said adaptor and said other pair of sides of said channel members to limit said tubular member and said adaptor against relative transverse movement between said channel members.

2. The structure of claim 1 wherein said adaptor includes a pair of parallel surfaces in mating engagement with the edges of the other adjacent pair of sides to limit rotation of said adaptor and said tubular member.

3. The structure of claim 2 wherein a shoulder extends perpendicularly outwardly of each of said parallel surfaces and matingly engages the inner surfaces of said other pair of channel sides.

4. The structure of claim 3 wherein an insulative sleeve embraces said tubular member between the opposite pairs of adjacent channel sides, and an insulative washer embraces said tubular member at each end in mating engagement with the opposite ends of said insulative sleeve, and a coil unit disposed on said insulative sleeve and between said pair of insulative washers.

5. The structure of claim 4 wherein said plunger includes a push rod extending axially through said, adaptor and having a doll on its outer end, and a cushion element embracing said push rod and disposed between said plunger and the inner end of said adaptor within said tubular member.

6. The structure of claim 1 and a stop plate positioned in the path of said plunger and secured to said pair of channel members, means for selectively positioning said stop plate relative to said pair of channel members to selectively limit the travel of said plunger.

7. The structure of claim 6 and a second pair of spaced apart oppositely facing metalic channel members disposed adjacent said first pair of channel members, an insulator terminal board extending between said first and second pair of channel members and means securing said first and second pairs of channel members to said stop plate and said terminal board to form a unitary heat sink and electrical conductor.

8. The structure of claim 7 wherein said stop plate is a channel-shaped member and is disposed at a right angle to each of the channel members in each of said first and second pairs of channel members, and a bracket extending from each leg of said stop plate channel member to the bottom wall of the outer channel member of the adjacent pair of channel members.

9. The structure of claim 8 and a sheet of cushioning material is provided on the inner side of the bottom wall of the stop channel member to provide a cushion for said movable plungers.

10. The structure of claim 9 and said means for selectively positioning said stop plate relative to said pair of channel members is further defined as said brackets having a slot formed therein and a fastener element extending through said slot at the desired point and secured to the adjacent side leg of said stop channel member.

11. The structure of claim 1 wherein said plunger includes a push rod extending axially through said adaptor and having a doll on its outer end, and a collar longitudinally adjustably mounted on push rod between said adaptor and said doll to selectively limit the retraction of said push rod.

12. The structure of claim 11 wherein a cushioning element is provided on said push rod between said adaptor and said collar to cushion said valve assembly upon retraction of said push rod.

13. A player piano key actuating assembly, comprising,

a first pair of spaced apart oppositely facing channel members,

a second pair of spaced apart oppositely facing channel members in alignment with said first pair of channel members,

at least one solenoid valve assembly in said first pair of channel members and having a push rod extending outwardly between said channel members,

at least one solenoid valve assembly in said second pair of channel members and having a push rod extending outwardly between said channel members and between the channel members of the first pair of channel members and adjacent its solenoid valve assemblies, said push rod of said solenoid in said second channel members having an outer end positioned adjacent the outer end of the push rod of the solenoid in said first channel members.

14. The structure of claim 13 wherein a mounting plate extends between and is connected to the base portion of adjacent channel members in each of said first and second pair of channel members to maintain said first and second pair of channel members in spaced apart relationship, and an insulative terminal sheet member on each of the base portions of the other adjacent channel members in said first and second pair of channel members.

15. The structure of claim 14 wherein a collar member is provided on each of said push rods and means is provided for selectively locking said collar member to said push rod whereby said collar member is longitudinally adjustable relative to said push rod to limit the retraction of said push rod.

16. The structure of claim 14 wherein said solenoids comprise,

a metal tube having an annular flared one end portion,

an insulative washer on said tubular member bearing against said flared one end portion,

an insulative sleeve embracing said tubular member and engaging said washer, said tubular member having an annular groove remotely of said flared one end portion,

a second insulative washer embracing said tubular member and seated in said groove and in mating engagement with the other end of said sleeve,

an adaptor press fitted into said flared one end of said tubular member,

a plunger movable in said tubular member and having a push rod extending outwardly through said adaptor, and

a coil mounted on said sleeve between said first and second insulative washers.

3/1964 Fauser 335-255 XR 2/1967 Flentge 335255 GEORGE HARRIS, Primary Examiner.

US. Cl. X.R. 

